A cased component has a chip in the interior, which chip can contain an integrated circuit or on which chip, for example, metallic structures for producing an acoustic wave are arranged. The chip is generally arranged on a carrier substrate and surrounded by a casing. In most cases, the coefficient of thermal expansion of the chip differs from the coefficient of thermal expansion of the material of the carrier substrate and/or of the housing. As a result, in the event of temperature changes, result, mechanical loadings of the internal electrical connections between chip and carrier substrate occur, which can lead to failures of the component depending on the loading intensity. Furthermore, the temperature-dictated stress or else mechanical strains introduced externally, for example via a printed circuit board, can impermissibly influence the electrical characteristic variables of sensitive chips, for example of MEMS (microelectromechanical systems) sensors, surface acoustic wave (SAW)/bulk acoustic wave (BAW) filters or quartz/silicon resonators.
Highly sensitive chips of the type mentioned are predominantly incorporated into cavity casings formed from a ceramic or a polymer material. The component can subsequently be closed with a metal cover by adhesive bonding, soldering or welding. Such a design of a cased component imposes limits on the miniaturization that can be achieved.
Less stress-sensitive components are therefore often adhesively bonded to a carrier element, for example a frame structure (leadframe) or a panel, electrically contact-connected to the carrier element and directly encapsulated with a thermosetting plastic molding compound. In the case of this design, however, an unimpeded stress transfer as a result of internally thermomechanically mismatched materials or else a stress transfer from outside to the sensitive chip takes place, as a result of which the accuracy and reproducibility of the electrical parameters of the component are impaired. In particular, reliability problems arise with regard to the functional capability of the chip in the event of temperature cycles.
It is desirable to specify a cased electrical component in which a stress exerted on a chip of the component on account of thermomechanical loading is reduced. Furthermore, the intention is to specify a method for producing a cased electrical component in which the stress on a chip in the interior of the housing that is exerted on account of a thermomechanical loading is reduced.
A cased electrical component comprises a carrier substrate, a spring device which is arranged on the carrier substrate, a chip, which is coupled to the spring device at a first side of the chip, and a covering element, which is arranged on the carrier substrate. The covering element is arranged over the chip in such a way that the covering element touches the chip at least at a second side of the chip, said second side being different from the first side.
The component has a small space requirement and a high impermeability with respect to influences from the environment. With the use of a carrier substrate composed of a ceramic and a covering element having a layer composed of metal, a continuous metal and ceramic encapsulation without abutment joints can be realized circumferentially around the chip. What is essential in this case is, in particular, the fixed and impermeable connection at the transition between ceramic and metal, which can be realized by means of a sputtering process, for example.